Geomorphological Thresholds Gullying in Kechik Basin, Northeast of Golestan Province

Gullying is a complicated process controlled by so many factors and dependent on thresholds which cause its formation. It is important to have innovation in application of an appropriate model in order to make spatial formation predication and development of gullying in addition to determining geomorphologic thresholds which affect it and also make a zonation of this process. Using existing materials in Kechic watershed located in the northeast of Golestan province which is 3598/8 acre in size, we selected 35 gullies as samples in a field survey. Then, we wrote down their morphometric and quantitative characteristics. Analyzing satellite images and basic maps, we produced maps for 9 geomorphologically influential factors in gullying in GIS. Proportion of every gully at geomorphologic factor of maps was determined. Afterwards, produced maps were turned into two categories of gullying and non-gullying. Finally, having produced the related maps for each factor and map overlaying, we produced the ultimate map and thresholds. The results showed that all geomorphologic factors, based on their effect range and thresholds, are involved in the formation and development of gully in the area.